The invention relates to a linear burner supplied with fuel gas and oxygen-carrying air.
In the field, such a burner is also referred to as a burner rail.
An example of a burner of this type may be found in Patent Application FR 2,641,601 or WO-a-900 7680.
This is a burner comprising at least one row of jets, each jet extending through an opening made in a wall of a body of the burner forming an air-distribution chamber on the inside, with which the said jets communicate, these jets being arranged substantially radially relative to a longitudinal direction in which the body of this burner extends.
This type of burner has the advantage of offering a very extensive range of heating power.
Its use is widespread particularly in the food industry.
It permits good distribution of the heating zone and, a priori, a relatively accurate possible adjustment of the power, bearing in mind the multiplication of the jets and their distribution.
In order to enhance variation of the working width of the burner, that is to say to adapt the number of jets which have to operate to the heating requirements, the abovementioned publication WO-A-900 7680 proposes mechanically varying the volume of the body of the burner so as to connect a larger or smaller number of jets to the supplies provided for this purpose.
Such mechanical adjustment using moving pieces does, however, present certain disadvantages linked particularly to problems of leaktightness and, if appropriate, mechanical behavior of the drive pieces, the pistons provided for this purpose being capable, in particular, of becoming immobilized.
Moreover, on the burner in question, it may be difficult to know the useful clear volume of the body of the burner and thus the available heating power. Furthermore, under certain conditions, flame instability could occur, drops in pressure proving to be unequally distributed inside the body.
It will also be noted that such an apparatus requires the production of an assembly comprising a large number of pieces and, particularly, the presence not only of an air-distribution chamber but also, arranged inside, of a fuel gas distribution chamber, the jets then being supplied "globally" via this second chamber.